Attempts have recently been made, for the purpose of improving comfort in wearing soft contact lenses, to add a polymer that improves lens surface lubricity, to soft contact lens care preparations and packaging solutions. With such a conventionally proposed polymer, however, the improvement lasts only insufficiently and, in particular, the wearing comfort is impaired when the lenses are worn throughout the day, so that further improvement is desired.
Commercially-available lens care preparations used for storing soft contact lenses are usually disinfectant for preventing proliferation of bacteria and ameba during storage. As disclosed in Non-patent Publication 1, however, such preparations are not actually effective for ameba, and infections caused by amebic adhesion have been social concerns, to which sufficient solutions are yet to be found. This is because the soft contact lenses are made of hydrogel, to which surface functionalities, such as lubricity and inhibition of amebic adhesion, are hard to be imparted with durability through a simple process.
Polymers having a phosphorylcholine-like group are known to have excellent biocompatibilities, such as blood compatibility, ability to inactivate complements, and nonadsorbability of biomaterials, due to their phospholipid-like structure derived from biomembranes, and also have various excellent properties, such as extremely high hydrophilicity and moisture-retaining property. In view of this, researches have actively been made concerning synthesis and applications of polymers having a phosphorylcholine-like group for the purpose of development of biomaterials.
For example, Patent Publication 1 proposes to use a polymer obtained by polymerization of a monomer having a phosphorylcholine group and a monomer having a hydrophobic alkyl group, in a contact lens wetting solution.
However, this polymer has a problem of insufficient lubrication, and has not been investigated for amebic adhesion inhibitory effect, which is in fact revealed to be insufficient.
Patent Publication 2 proposes a copolymer of a monomer having a phosphorylcholine group and another hydrophilic monomer. This copolymer, however, is highly hydrophilic, so that it is discharged with lacrimal fluid while the lenses are worn, and hard to be sustained sufficiently.
Patent Publication 3 discloses addition of a copolymer of a monomer having a phosphorylcholine group and butylmethacrylate to a contact lens packaging solution. However, the butyl group in the copolymer has weaker coagulation power compared to a long chain alkyl group, and causes less change in finger feel in an aqueous solution, so that sufficient improvement in lens wearing comfort is not achieved.
Patent Publication 4 discloses achievement of excellent cleansing power by using a copolymer of a monomer having a phosphorylcholine group and alkylmethacrylate in a contact lens cleansing solution. However, the copolymer has not been investigated for capability of imparting lens surface lubricity or amebic adhesion inhibitory effect, which are in fact revealed to be insufficient.    Patent Publication 1: WO 02/15911 A1    Patent Publication 2: US 2008/0314767 A1    Patent Publication 3: US 2009/0100801 A1    Patent Publication 4: JP 2003-005136-A    Non-patent Publication 1: Eye & Contact Lens 36(1), p 26-32 (2010)